JPH0380302B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor using a novel electrophotographic photosensitive material, and more specifically to an electrophotographic photoreceptor containing a disazo pigment having a specific molecular structure in a photoconductive layer. It's about the body. [Prior Art] Pigments and dyes exhibiting photoconductivity have been published in numerous publications. For example, “RCA Review” Vol.23, P.413~
P.419 (September 1962), there was a presentation on the photoconductivity of phthalocyanine pigments, and electrophotographic photoreceptors using these phthalocyanine pigments were shown in U.S. Patent No. 3397086 and U.S. Patent No. 381611, etc. ing. In addition, as organic semiconductors used in electrophotographic photoreceptors, for example, US Pat.
4315983, U.S. Patent No. 4327169 and “Reseach Disclosure” 20517 (May 1981), pyrylium dyes, U.S. Patent No. 3824099, methine squaritate dyes, U.S. Patent No. 3898084 Publication, U.S. Patent No.
Examples include disazo pigments disclosed in Publication No. 4251613 and the like. Such organic semiconductors are easier to synthesize than inorganic semiconductors, and can be synthesized as compounds that have photoconductivity for light in the required wavelength range. An electrophotographic photoreceptor formed on a conductive support has the advantage of improved color sensitivity, but only a few of them are practical in terms of sensitivity and durability. [Problems to be Solved by the Invention] An object of the present invention is to provide a novel photoconductive material. Another object of the present invention is to provide an electrophotographic photoreceptor that can be used in all existing electrophotographic processes and has practical high sensitivity characteristics and stable potential characteristics during repeated use. [Means for Solving the Problems] In the electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive substrate according to the present invention, the photosensitive layer has the following general formula:
(1), (In the formula, A is a coupler residue having a phenolic OH group; Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each a phenylene which may have a substituent, a divalent condensed polycyclic aromatic group, or a divalent An electrophotographic photoreceptor is provided, which contains a disazo pigment represented by the following heterocyclic group; n is 0 or 1. In the above general formula (1), Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄
Specifically, for example, a divalent condensed polycyclic aromatic group such as phenylene, biphenylene, naphthylene, anthranilene, fluorenylene, divalent fluorenone, or quinoline, divalent carbazolyl, divalent
Examples include divalent heterocyclic groups such as divalent benzoxazole. These groups include, for example, alkyl groups (methyl, ethyl, propyl, etc.), aralkyl groups (benzyl, phenethyl, naphthylmethyl, etc.),
Substituted with aryl groups (phenyl, diphenyl, naphthyl, etc.), alkoxy groups (methoxy, ethoxy, butoxy, etc.), halogens (chlorine, bromine, iodine, fluorine), cyano groups, isyl groups (acetyl, benzoyl, etc.), nitro groups may be done. Furthermore, the phenolic nature of A in general formula (1) is
Examples of coupler residues having an OH group include the following general formulas (2) to (8): (In _the formula _, Represents a residue that together with a nitrogen atom forms a cyclic amino group; R ₃ and R ₄ each represent an optionally substituted alkyl, aralkyl, or aryl; Y represents a divalent aromatic hydrocarbon or a residue that forms a divalent heterocyclic group together with a nitrogen atom; R ₅ and R ₆ are a hydrogen atom, an alkyl, aralkyl, aryl, or a heterocyclic ring which may have a substituent. represents a group, and R ₅ and R ₆ are 5 to 5 along with the central carbon.
Indicates a residue forming a 6-membered ring. This 5- to 6-membered ring may have a fused aromatic ring; R ₇ and R ₈ are each a hydrogen atom and an alkyl that may have a substituent. , aralkyl, aryl or heterocyclic group). Examples of the polycyclic aromatic ring and heterocycle of X include naphthalene, anthracene, carbazole, benzcarbazole, dibenzofuran, benzonaphthofuran, and diphenylene sulfide. In addition, in the case of R ₁ and R ₂ , alkyl is, for example, methyl,
Ethyl, propyl, butyl, etc. are shown, aralkyl is, for example, benzyl, phenethyl, naphthylmethyl, etc., and aryl is, for example, phenyl, diphenyl, naphthyl, anthryl, etc. In particular, R ₁ is hydrogen, R ₂ is a halogen at the O-position,
Compounds having a structure that is a phenyl group having an electron-withdrawing group such as nitro, cyano, or trifluoromethyl and an alkyl group such as methyl, ethyl, or butyl are preferred. Examples of the heterocycle include carbazole, dibenzofuran, benzimidazolone, benzthiazole, thiazole, and pyridine. Specific examples of R ₃ and R ₄ include the same ones as exemplified above for R ₁ and R ₂ . Also, the alkyl groups of R ₁ , R ₂ , R ₃ and R ₄ above,
The aralkyl group, aryl group, and heterocyclic group may further include other substituents, such as the aforementioned alkyl group, alkoxy group, halogen atom, nitro group, cyano group, or dimethylamino, siethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, It may be substituted with a substituted amino group such as pyrrolidino. In the definition of Y, the divalent aromatic hydrocarbon group includes, for example, a monocyclic aromatic hydrocarbon group such as O-phenylene, O-naphthylene, perinaphthylene,
Examples include fused polycyclic aromatic hydrocarbon groups such as 1,2-antrylene and 9,10-phenanthrylene. In addition, examples of forming a divalent heterocycle with a nitrogen atom include a 3,4-pyrazolediyl group, a 2,3-pyridinediyl group, a 4,5-pyridinediyl group, and a 6,7-indazolediyl group. basis,
5,6-benzimidazolediyl group, 6,7-
Examples include 5- to 6-membered heterocyclic divalent groups such as quinolinediyl group. Examples of the aryl group or heterocyclic group for R ₅ and R ₆ include phenyl, naphthyl, anthryl, pyrenyl;
Examples include pyridyl, thienyl, furyl, carbazolyl and the like. These may be substituted with the substituents described above. Also, R ₅ and R ₆ are together 5~
Residues forming a 6-membered ring are shown. This 5- to 6-membered ring may have a fused aromatic ring. Examples of such groups include cyclopentylidene, cyclohexylidene, 9-fluorenylidene, 9-xanthenylidene, and the like. Specific examples of alkyl, aryl, and aralkyl for R ₇ and R ₈ include the same ones as mentioned above. Heterocycles include carbazole, dibenzofuran, benzimidazolone, benzthiazole,
Examples include thiazole and pyridine. These may be substituted with the substituents described above. The specific example of X in formulas (7) and (8) is the same as that of X in formula (2) above. In particular, the ring to which X is attached is an anthracene ring, a benzcarbazole ring,
A carbazole ring is preferred. In particular, the benzcarbazole ring has a great effect of expanding the spectral sensitivity range to a long wavelength range, and is suitable for producing a photoreceptor having high sensitivity in the semiconductor laser range. According to the present invention, although not bound by theory, the disazo pigment of general formula (1) above is located at the center of the skeleton.

[Formula] By having a group and one or two vinylene structures, the photoconductivity of the pigment is improved, and either or both of the carrier generation efficiency and transportability are improved, resulting in sensitivity and potential stability during long-term use. It is thought that the quality is ensured. In addition, high sensitivity and a long wavelength in the spectral sensitivity range are achieved, making it possible to apply it to high-speed copying machines, laser beam printers, LED printers, liquid crystal printers, etc. Furthermore, stable potential is maintained regardless of the previous history of the photoreceptor. A stable and beautiful image can be obtained. Representative examples of disazo pigments used in the present invention are listed below. The above disazo pigments can be used alone or in combination of two or more. Further, the disazo pigment of general formula (1) is, for example, the following formula:
H ₂ N−Ar ₁ −CH=CH−Ar ₂ −NH−Ar ₃ −(CH=
A diamine having a secondary amino represented _by CH- _Ar4- ) _oNH2 (wherein _Ar1 , _Ar2 , _Ar3 , _Ar4 and n are the same as above) is tetrazotized and simultaneously nitrosated by a conventional method, The corresponding coupler is then coupled in an aqueous system in the presence of an alkali, or the tetrazonium salt of the diamine is once isolated in the form of a borofluoride salt, zinc chloride double salt, etc., and then dissolved in a suitable solvent such as N,N-dimethyl. formamide,
It can be easily produced by coupling with a coupler in a solvent such as dimethyl sulfoxide in the presence of an alkali. Next, a typical synthesis example of the disazo pigment used in the present invention will be shown. Synthesis Example 1 (Synthesis of Disazo Pigment No. 1 exemplified above) Add 80 ml of water and 16.6 ml (0.19 mol) of concentrated hydrochloric acid to a 500 ml beaker and add diamine while cooling in an ice water bath. Add 8.74g (0.029mol), stir, and lower the liquid temperature to 3℃
And so. Next, a solution prepared by dissolving 6.2 g (0.090 mol) of sodium nitrite in 7 ml of water was added dropwise over 10 minutes while controlling the temperature within the range of 3 to 10°C, and after the addition was completed, the mixture was stirred for an additional 30 minutes at the same temperature. Carbon was added to the reaction solution to obtain a tetrazotized solution. Next, add dimethylformamide to 2 beakers.
Pour 700ml, add 53.6 (0.53 mol) of triethylamine, and add 3-hydroxy-2-naphthoic acid anilide.
16.06 g (0.061 mol) was added and dissolved. Cool this coupler solution to 6℃ and reduce the liquid temperature to 6-10℃.
Add the above-mentioned tetrazotization solution while controlling the temperature at
The mixture was added dropwise over 30 minutes with stirring, and then stirred at room temperature for 2 hours and further left overnight. The reaction solution was filtered and then washed with water to obtain a water paste containing 23.20 g of crude pigment in terms of solid content. Next, stirring was repeated four times at room temperature using 400 ml of N,N-dimethylformamide. after that
After repeating stirring twice with 400 ml of methyl ethyl ketone, the purified pigment was dried under reduced pressure at room temperature.
21.7g was obtained. The yield was 85.0%. Melting point 300
°C Elemental analysis Calculated value (%) Experimental value (%) C 73.79 73.83 H 4.36 4.31 N 12.75 12.65 The synthesis methods of typical pigments have been described above.
Other disazo pigments represented by general formula (1) are also synthesized in the same manner. The coating containing the disazo pigment described above exhibits photoconductivity and can therefore be used in the photosensitive layer of the electrophotographic photoreceptor described below. That is, in a specific example of the present invention, an electrophotographic photoreceptor is prepared by forming a film of the above-mentioned disazo pigment on a conductive support by vacuum evaporation, or by dispersing it in a suitable binder and forming a film. can do. In a preferred embodiment of the present invention, the photoconductive coating described above can be applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5μ or less, in order to shorten the range of the generated charge carriers. Preferably
A thin film layer having a thickness of 0.01 to 1 μm is preferable. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection. The charge generation layer can be formed by dispersing the above-mentioned compound in a suitable binder and coating it on the substrate, or it can be obtained by forming a vapor deposited film using a vacuum vapor deposition apparatus. . The binder that can be used when forming the charge generation layer by coating can be selected from a wide range of insulating resins.
It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane. Examples include insulating resins such as resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The amount of resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and dichlorohexanone, N,N-dimethylformamide,
Amides such as N,N-dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogens such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Mayer bar coating, plaid coating, roller coating, and Curtin coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30℃ to 200℃ for 5 minutes to 2
It can be carried out stationary or under blown air for a period of time within a range of hours. The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. At this time, this charge transport layer may be laminated on or under the charge generation layer. When the charge transport layer is formed on the charge generation layer, the substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is substantially in the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. Preferably, it is insensitive to. The term "electromagnetic waves" used herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both trap each other, resulting in a decrease in sensitivity. Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4,7-trinitro-9-fluorenone. , 2, 4, 5, 7-
Tetranitro-9-fluorenone, 2,4,7-
trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone,
Examples include electron-withdrawing substances such as 2,4,8-trinitrothioxanthone, and polymerization of these electron-withdrawing substances. Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
N-Methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-
3-methylidene-10-ethylphenothiazine,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, P-diethylaminobenzaldehyde-N,N-diphenylhydrazine, P-diethylaminobenzaldehyde-N
-α-naphthyl-N-phenylhydrazone, P-
Pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone hydrazones such as 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1
-Phenyl-3-(P-diethylaminostyryl)
-5-(P-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]- 3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[6-methoxy-pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1- [Pyridyl(3)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[Lepidyl(2)]-3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-
3-(P-diethylaminostyryl, 4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(P-diethylaminostyryl)-4-methyl-5
-(P-diethylaminophenyl)pyrazoline,
1-Phenyl-3-(α-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(P-diethylaminostyryl)
-6-diethylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2
Thiazole compounds such as -(P-diethylaminostyryl)-6-diethylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N -diethylamino-2-methylphenyl)heptane, 1,
Polyarylalkanes such as 1,2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, 4-diphenylamine-4″-
Stilbene compounds such as methoxystilbene, 4″-diethylaminostyryl-3-(9-ethyl)carbazole, triphenylamine, poly-N-
Examples include vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin. In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium amorphous silicon, and cadmium sulfide can also be used. Moreover, these charge transport substances may be one or two types.
More than one species can be used in combination. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N- Mention may be made of organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene, polyvinylpyrene. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5-30μ, but the preferred range is 8-20μ. When forming the charge transport layer by coating, an appropriate coating method as described above can be used. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive substrate. As the substrate having the conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics (such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic, conductive particles (e.g. aluminum powder, tin oxide, zinc oxide, titanium oxide, carbon black,
a substrate in which silver particles, etc.) are coated on plastic or the above-mentioned conductive substrate together with a suitable binder;
A substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon
610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 to 5μ, preferably 0.5 to 3μ.
is appropriate. When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones. On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged.
After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transporting substance is used. When using a photoreceptor in which a conductive layer, a charge transport layer, and a charge generation layer are laminated in this order, if the charge transport substance is an electron transport substance, the surface of the charge generation layer must be negatively charged, and exposure after charging is required. Then,
In the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer and then reach the substrate. On the other hand, holes generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a positively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones. On the other hand, when the charge generation layer is made of a hole transporting substance, the surface of the charge generation layer must be positively charged, and when exposed to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. and then reaches the base. On the other hand, electrons generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used. In another specific example of the present invention, organic photoconductive materials such as the aforementioned hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamines, poly-N-vinylcarbazoles, etc. The photosensitive film may contain the above-mentioned disazo pigment as an enhancer for photoconductive substances and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium. This photosensitive film is formed by coating these photoconductive substances and the above-mentioned disazo pigment together with a binder. Another specific example of the present invention is an electrophotographic photoreceptor containing the above-mentioned disazo pigment and a charge transport material in the same layer. In this case, in addition to the above-mentioned charge transport materials, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used. The electrophotographic photoreceptor of this example can be prepared by dispersing the aforementioned disazo pigment and charge transfer complex compound in a polyester solution in tetrahydrofuran, and then forming a film thereon. The pigment used in both photoreceptors has the general formula
It contains at least one type of pigment selected from the disazo pigments shown in (1), and its crystal form may be amorphous or crystalline. Furthermore, if necessary, two or more types of disazo pigments represented by the general formula (1) may be used in combination for the purpose of increasing the sensitivity of the photoreceptor or obtaining a panchromatic photoreceptor by using a combination of pigments with different light absorption. Alternatively, it can be used in combination with a charge generating substance selected from known dyes and pigments. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers and CRTs.
Printers, LED printers, LCD printers,
It can also be widely used in electrophotographic applications such as laser engraving. The present invention will be explained below with reference to Examples. Examples 1 to 62 An ammonia aqueous solution of casein (11.2% casein, 1 g of aqueous ammonia, 222 ml of water) was coated on an aluminum plate using a Mayer bar so that the film thickness after drying was 1.0 μm and dried. Next, 5 g of the above-mentioned disazo pigment No. 1 was added to 95 ml of ethanol with butyral resin (butyralization degree 63).
Add 2g (mol%) to the dissolved liquid and add 2g with a sand mill.
Spread out time. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying was 0.5 μm, and dried to form a charge generation layer. Then the structural formula 5 g of hydrazone compound and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were added to benzene.
The photoreceptor of Example 1 was prepared by dissolving the solution in 70 ml and coating it on the charge generation layer using a Mayer bar so that the thickness after drying was 12μ, and drying to form a charge transport layer. Photoreceptors corresponding to Examples 2 to 62 were prepared in exactly the same manner using other exemplary pigments shown in Table 1 in place of disazo pigment No. 1. The electrophotographic photoreceptor thus prepared was statically charged with corona at -5 kV using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd., and held in a dark place for 1 second, then at an illuminance of 2 lux. It was exposed to light and its charging characteristics were investigated. As for the charging characteristics, the surface potential (V ₀ ) and the exposure amount (E1/2) required to attenuate the potential to 1/2 when dark decayed for 1 second were measured, and the results are shown in Table 1.

【table】

【table】

[Table] Comparative Examples 1 to 7 In place of the exemplified disazo pigments (1), (3), and (4), the central skeleton of the pigment was

Azo pigment No. 2 described in the published patent publication No. 58-132242, in the form of [Formula]
Comparative Examples 1, 2, and 3 were created using pigments No. 1 and No. 3. Next, exemplified disazo pigments (1), (22),
In place of (35) and (64), the central skeleton of the pigment is

【formula】

【formula】

【formula】

Comparative Examples 4, 5, 6, and 7 were prepared using the comparative pigments shown in the following formula. For Comparative Examples 1 to 7 using Comparative Pigments 1 to 7, charge measurement was performed in the same manner as in Example 1. Table 2 shows the characteristics of comparative examples compared to the present invention.

[Table] * Extracted from the data in Table 1 As is clear from the results in Table 2, the photoreceptor of the present invention has a central skeleton of the pigment.

It has been confirmed that electrophotographic sensitivity is significantly improved by having the group [Formula] and one or more vinylene groups. Examples 63 to 68 Using the photoreceptors used in Examples 1, 3, 4, 22, 42, and 65, fluctuations in bright area potential and dark area potential during repeated use were measured. The measurement method is as follows. The photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a −5.6 kV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven. Using this copier, the initial bright area potential (V _L ) and dark area potential (V _D ) were set to around -100V and -600V, respectively, and the bright area potential (V _L ) and dark area potential after being used 5000 times. (V _D ) was measured. The results are shown in Table 3.

【table】

[Table] Example 69 On the charge generation layer prepared in Example 1, 2,
A coating solution prepared by dissolving 5 g of 4,7-trinitro-9-fluorenone and 5 g of poly-4,4'-dioxydiphenyl-2,2'-propane carbonate (molecular weight 300,000) in 70 ml of tetrahydrofuran was dried. It was coated at a coating weight of 10 g/m ² and dried. The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the charging polarity was set. The results are shown in Table 4. Table 4 V ₀ 600 volts E1/2 3.7lux.sec Example 70 A polyvinyl alcohol film with a thickness of 0.5 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the dispersion of the disazo pigment used in Example 1 was placed on the polyvinyl alcohol layer formed previously.
It was coated with a Mayer bar so that the film thickness after drying was 0.5μ, and dried to form a charge generation layer. Then, the structural formula A solution prepared by dissolving 5 g of pyrazoline compound and 5 g of polyacrylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 70 ml of tetrahydrofuran was placed on the charge generation layer to determine the thickness of the dry film.
It was applied to a thickness of 10μ and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown in Table 5. Table 5 V ₀ : -580V E1/2: 4.0llx・sec Initial After 5000 sheets of durability V _D V _L V _D V _L -600V -100V -630V -125V From the results in Table 5, the present invention has good sensitivity. can be,
Moreover, the potential stability during long-term use is also good. Example 71 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100 microns and dried to form a subbing layer with a thickness of 0.5 microns. Next, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly-N-vilcarbazole (number average molecular weight 300,000) were dissolved in 70 ml of tetrahydrofuran to form a charge transfer complex. This charge transfer complex compound and the above-mentioned disazo pigment No. 131g
, polyester resin (Vylon: manufactured by Toyobo) 5
g was dissolved in 70 ml of tetrahydrofuran and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12 microns, and dried. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown in Table 6. However, the charging polarity was determined. Table 6 V ₀ : 590V E1/2 : 4.4lux.sec Example 72 The charge transport layer and charge generation layer of Example 1 were sequentially applied on the casein layer of the casein layer-coated aluminum substrate used in Example 1. A photoreceptor was prepared in exactly the same manner as in Example 1, except that the order of the laminated layers was different, and the charging was measured in the same manner as in Example 1. However, the charging polarity was determined. Charging characteristics are shown in Table 7. Table 7 V ₀ 605V E1/2 4.8lux.sec Example 73 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 22.2 ml of water) was coated on an aluminum cylinder using the dip coating method, and dried. A subbing layer with a coating weight of 1.0 g/m ² was formed. Next, 1 part by weight of the above-mentioned disazo pigment No. 43, Petitral resin (Eslec BM-2: Sekisui Chemical Co., Ltd.)
1 part by weight) and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a Pall mill disperser. This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generation layer. The film thickness at this time was 0.3 microns. Next, 1 part by weight of the hydrazone compound used in Example 1, 1 part by weight of polysulfone resin (P1700: manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene.
Parts by weight were mixed and dissolved by stirring with a stirrer. This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The film thickness at this time was 12 microns. A -5 kV corona discharge was applied to the photoreceptor thus prepared. The surface potential at this time was measured (initial potential V ₀ ). Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay V _k ). Sensitivity is the exposure amount (E1/2, microjoule/cm ² ) required to attenuate the potential V _k by 1/2 after dark decay.
It was evaluated by measuring. At this time, the light source was a gallium/aluminum/arsenic ternary semiconductor laser (output: 5 mW, oscillation wavelength 778 nm).
was used. These results were as follows. V ₀ : -520 volts V _k : 94% E1/2: 1.2 microjoules/ ^cm Second, a laser beam printer (Canon LBP-CX), which is a reversal development type electrophotographic printer equipped with the same semiconductor laser as above. ), the above-mentioned exposed body was replaced with an LBP-CX photosensitive body, and an actual image forming test was conducted. The conditions are as follows. Surface potential after primary charging: -700V, surface potential after image exposure: -150V (exposure amount 2μJ/cm ² ), transfer potential;
700V, developer polarity: negative polarity, process speed: 50mm/sec, development conditions (development bias): -
450V, image exposure scan method; image scan,
Exposure before primary charging: 50 lux.sec full red exposure. Image formation was performed by line-skipping a laser beam in accordance with character and image signals, and good prints were obtained for both characters and images.

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor in which a photosensitive layer is provided on a conductive substrate, the photosensitive layer has the following general formula (1). (In the formula, A is a coupler residue having a phenolic OH group; Ar ₁ , Ar ₂ , Ar ₃ and rr ₄ are each a phenylene which may have a substituent, a divalent condensed polycyclic aromatic group, or a divalent An electrophotographic photoreceptor comprising a disazo pigment represented by the following heterocyclic group; n is 0 or 1. 2 A in the above general formula (1) is the following general formula (2) to (8)
An electrophotographic photoreceptor according to claim 1, which is represented by: (In the formula, X is a residue that is fused with a benzene ring to form a polycyclic aromatic ring or a heterocycle; R ₁ and R ₂ are hydrogen,
Indicates an optionally substituted alkyl, aralkyl, aryl or heterocyclic group, or a residue which together with a nitrogen atom forms a cyclic amino group;
R ₃ and R ₄ each represent alkyl, aralkyl, or aryl which may have a substituent; Y represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group together with the nitrogen atom; Indicates the residues that form;
R ₅ and R ₆ represent a hydrogen atom, an alkyl, aralkyl, aryl, or a heterocyclic group which may have a substituent, and R ₅ and R ₆ represent a residue that forms a 5- to 6-membered ring together with the central carbon. This 5- to 6-membered ring shown may have a fused aromatic ring; R ₇ and R ₈ each represent a hydrogen atom, an alkyl, aralkyl, aryl, or a heterocyclic group which may have a substituent. ). 3. The photosensitive layer is of a functionally separated type consisting of a charge generation layer and a charge transport layer, and the charge generation layer has the above general formula.
An electrophotographic photoreceptor according to claim 1, which contains a disazo pigment represented by (1). 4 R ₁ in the above general formula (2) is hydrogen, and R ₂
is the general formula The electrophotographic photoreceptor according to claim 2, wherein R ₉ is a substituted phenyl represented by the following formula: (wherein R 9 is a substituent selected from halogen, nitro, cyano, trifluoromethyl, and acyl). 5 In the above general formula (2), R ₁ is a hydrogen atom,
R ₂ is a phenyl group which may have a substituent,
X together with the benzene ring forms the following group: An electrophotographic photoreceptor according to claim 2, which forms an electrophotographic photoreceptor.